Both airports have been reopened, with Danish police unable to confirm origin of drones.
Members of a support group say they help their friends through "devastating" journeys.
The city hopes to offset the "environmental burden" of tourism with rewards for eco-friendly travellers.
Danes recount watching in horror as the historic Borsen went up in flames.
The historic 17th Century building in Denmark's capital was engulfed in flames on Tuesday.
The pledge comes after a huge blaze devastated the 17th-Century landmark on Tuesday.
There was shock as the 17th Century building's iconic dragon spire collapsed in the fire.
Video posted on social media captured the iconic spire tumbling to the ground after fire ravages the building.
One of the Danish capital's most historic buildings has been engulfed in a raging fire.
